Reciprocating gripper for feeding sheets in rotary printing machines

ABSTRACT

A swing gripper and a guiding device for transferring and guiding relatively heavy, flexible sheets such as cardboard and the like between a feed table and an impression cylinder of a rotary printing press. The guiding device includes a plurality of rollers arranged to surround a sector of the outer periphery of the impression cylinder for guiding sheets received by the impression cylinder into close contact therewith without smearing or damaging the sheets. The swing gripper is rotatably mounted for swinging movement between the feed table and the impression cylinder and has guide rolls at the lower end thereof. During return movement of the swing gripper to the feed table, the swing gripper rollers engage the trailing end of a sheet being transferred by the impression cylinder to bend it in the direction of the impression cylinder.

United States Patent 1191 Abendroth 1 1 RECIPROCATING GRIPPER FOR FEEDING SHEETS IN ROTARY PRINTING MACHINES [75] Inventor: Paul Abendroth, Offenbach,

Germany [73] Assignee: Roland Offsetmaschinenfabrik Faber & Schleicher AG, Offenback/Main, Germany [22] Filed: Nov. 15, 1972 [21] Appl. N0.: 306,693

[30] Foreign Application Priority Data Nov. 15, 197] Germany 2156577 [52] US. Cl 101/232, 101/409, 101/416 R, 271/277 [51] Int. Cl B411 l/28, B65h 29/08 [58] Field of Search 101/232, 246, 409, 410,

101/411, 412, 408, 416 R; 271/51, 52, 53; 197/138 A, 138 R; 271/82 3,355,169 11/1967 Seyl ..27l/82 [451 Oct. 8, 1974 3,379,432 4/1968 Ruth 271/51 3,417,696 12/1968 K0611 et a1. 101/409 3,650,211 3/1972 Nentwich 101/409 FOREIGN PATENTS OR APPLICATIONS 1,162,352 8/1969 Great Britain 101/232 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Paul J. Hirsch Attorney, Agent, or Firm-Wolfe, Hubbard, Leydig, Voit & Osann, Ltd.

[ 5 7] ABSTRACT A swing gripper and a guiding device for transferring and guiding relatively heavy, flexible sheets such as cardboard and the like between a feed table and an impression cylinder of a rotary printing press. The guiding device includes a plurality of rollers arranged to surround a sector of the outer periphery of the impression cylinder for guiding sheets received by the impression cylinder into close contact therewith without'smearing or damaging the sheets. The swing gripper is rotatably mounted for swinging movement between the feed table and the impression cylinder and has guide rolls at the lower end thereof. During return movement of the swing gripper to the feed table, the swing gripper rollers engage the trailing end of a sheet being transferred by the impression cylinder to bend it in the direction of the impression cylinder.

7 Claims, 8 Drawing Figures PATENTED [1B1 81974 SHEEI 1 0F 4 Fig! PATENTED 81974 3.839.959

SHEU 2 (If 4 Fig. 2

PAIENTED DU 74 SHEEI 301 4 RECIPROCATING GRIPPER FOR FEEDING SHEETS IN ROTARY PRINTING MACHINES DESCRIPTION OF THE INVENTION The present invention relates generally to apparatus for transferring and guiding heavy sheets, such as cardboard and the like, in rotary printing machines. More particularly, the invention relates to a swing gripper and a guiding device for use in transferring sheets from a feed table to an impression cylinder of the printing machine.

Difficulties frequently have been encountered when printing relatively heavy sheets, such as cardboard, corrugated board, and plastic, in rotary printing machines. When such sheets are being transferred by the impression cylinder, they often do not readily conform to the curvature of the impression cylinder or remain in contact therewith, but instead tend to project in a tangential direction so as to interfere with components of the machine. Heretofore, conventional guide rails that have been provided about the impression cylinder of high speed printing machines have tended to impede movement of the sheets or mar the sheets and have not proved satisfactory. Moreover, in high speed printing presses, it is important that the swing gripper which transfers the sheet from the feed table to the grippers of the impression cylinder return to the feed table prior to the complete removal of the sheet from the feed table in order that it will be in position to immediately grip the next sheet at the feed table. During such return movement of the swing gripper, it generally strikes the protruding end of the previous sheet being transferred by the impression and as a result often causes markings or damage to the sheet.

It is an object of the present invention to provide a device which effectively guides relatively heavy flexible sheets into close contact with the impression cylinder of a high speed rotary printing press without significantly impeding movement of the sheets or damaging them.

Another object is to provide a guiding device as characterized above which prevents the sheets from contacting components of the printing machine and which eliminates relative sliding movement between the sheets and the guiding device.

A further object is to provide a swing gripper which transfers sheets from the feed table to the impression cylinder of the press and upon its return to the feed table engages the previous sheet being transferred by the impression cylinder and bends it in the direction of the impression cylinder without damaging or smearing of the sheet.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:

FIG. I is a diagrammatic side elevation view of a swing gripper and guiding device embodying the present invention showing the transfer of sheets between a feed table and an impression cylinder of a printing ma chine;

FIG. 2 is a diagrammatic side elevation view showing both the sheet receiving and transfer positions of the swing gripper;

FIG. 3 is a diagrammatic view showing the successive positions of the swing gripper as it returns from its transfer position to the sheet receiving position at the feed table;

FIG. 4 is an enlarged diagrammatic side elevational view of the lower portion of the swing gripper shown in FIG. 11;

FIG. 5 is a partial section view of the swing gripper as shown in FIG. 4;

FIGS. 6 and 7 are views comparable to FIG. 5, but showing alternative forms of roller arrangements for the swing gripper; and

FIG. 8 is a fragmentary sectional view of one of the rollers of the guiding device, illustrating the different forms of individual rolls which may be utilized.

While the invention is susceptible of various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed but, on the contrary, the intention is to cover all modifications, alternative constructions and equivalents, falling within the spirit and scope of the invention.

Referring more particularly to FIG. 1 of the drawings, there is shown a swing gripper l0 and a guiding device 11 embodying the present invention for transferring and guiding sheets from a feed table 12 to an impression cylinder 14 of a printing machine. The printing machine in this case is of the offset type having a blanket cylinder 15 which is interposed between the impression cylinder 14 and a printing cylinder (not shown) in a conventional manner. The feed table 12 may be equipped with conventional sheet transfer means for successively advancing sheets 16 in underlapped relationship. The upper sheet 16' and the next advancing sheet 16" are shown in FIG. 2. The sheets 16 may be made of relatively heavy flexible material such as cardboard, corrugated board, plastic or other like materials.

For the purpose of selectively engaging and releasing sheets 16, the swing gripper 10 has a rotatable arm 18 provided with a gripper member 19 and a gripper pad 20. The gripper member 19 in this case is formed with a gripping finger 21 and is rigidly clamped to a shaft 22 provided at the lower end of the arm 18 (FIG. 4). The gripper pad 20 is radially movable relative to the arm for engaging a sheet 16 against the gripper finger 21 at the feed table 12 and releasing the sheet after transfer to the impression cylinder 14. The arm 18 is clamped on a shaft 24 which is rotatable and radially movable with respect to the feed table 12 and impression cylinder I4 so that the gripper member 19 moves along one curved path 25 during transfer of a sheet from the feed table 12 to the impression cylinder 14 and along an elevated path 25" on its return to the feed table (FIG. 2). Such rotatable and oscillatory movement of the swing gripper 10 may be effected by appropriate drive means known to one skilled in the art.

For receiving and engaging successive sheets from the swing gripper 10, the impression cylinder 14 is provided with a rotatable gripper 30 and a gripper pad 31 (FIG. 2). The operation of the swing gripper is accurately timed so that the leading edge of a new sheet 16 is brought into position for transfer each time the impression cylinder grippers 30, 31 arrive at the transfer station. As the impression cylinder grippers 30, 31 engage the sheet, the sheet is simultaneously released by the grippers 19, of the swing gripper 10. The sheet is thereupon carried around the impression cylinder and the swing gripper continues along the path to a position well above the impression cylinder. At that point the swing gripper is moved away from the impression cylinder and its direction of movement reversed for return of the grippers 19, 20 to the feed plate along the path 25".

Since the sheets 16 are relatively heavy, they generally do not readily conform to the curvature of the impression cylinder 14, but instead, the trailing ends of the sheets tend to project in a tangential direction out from the impression cylinder. In conventional presses, the protruding ends of such sheets often are struck by portions of the machine as the sheet is carried around the impression cylinder or by the swing gripper on its return trip to the feed table, resulting in markings or damage to the sheet.

In accordance with the present invention, means are provided for guiding the sheets into close relation with the impression cylinder without impeding the transfer of the sheets or marking or damaging them. To this end, the guiding device 11 has a plurality of guide rollers 34, 35, and 36 arranged along an envelope surface 38 surrounding a sector of the outer periphery of the impression cylinder 14 and spaced a distance 39 therefrom. The guide roller 34 in this case is supported by means of a yoke 40 pivotably mounted at opposite sides of a journal 41 of the impression cylinder 14 (FIG. 2). The guide rollers 35, 36 are supported between suitable arms (not shown) pivotably attached on opposite sides of the axis of the first guide roller 34. Appropriate locking means may be employed for locking the roller support arm in a selected position with respect to the impression cylinder.

Each of the guide rollers 34, 35, and 36 preferably consist of a series of coaxially mounted individual rolls 42 which may be adjusted laterally depending upon the image to be printed. The rolls 42 of each roller may take various forms such as a flat cylindrical running surface 44 or round surfaces 45, 46 having conical or parallel sides, as illustrated in FIG. 8. While for purposes of illustration FIG. 8 discloses various designs for the rolls 42, generally the rolls of each roller 34, and 36 are of the same configuration. The rollers preferably are made of synthetic material, although alternatively, in order to improve the rolling conditions for specific materials to be printed, the outer periphery of the rolls may have a metallic coating 48, such as is also shown in certain of the rolls in FIG. 8. The rolls 42 of each roller are rotatably mounted on a shaft 49 and are maintained in spaced relation by spacers 50, with appropriate clamping members 51 holding the rolls in place on the shaft. By removing the clamping members 51, the rolls may be readily interchanged and repositioned at various axial locations on the shaft 49 so that a printer may select the proper position and shape of rolls according to the image to be printed.

To increase the effective range of sheet guidance, the guiding device 11 may be oscillated as a unit so that the rollers 34, 35, and 36 move back and forth along the envelope surface 53 between a feed table position and a blanket cylinder position. For that purpose, the support yoke oscillates an angular distance 55 indicated in FIG. 1 in order to deflect a sheet received by the impression cylinder 14 at an earlier point. Thereafter, the rollers of the guiding device 1 l are returned to their position adjacent the blanket cylinder at the approximate speed the sheet is being transferred by the impression cylinder. Up on reaching the position adjacent the blanket cylinder, the guiding device comes to a halt and remains at rest until the trailing end of the sheet being transferred around the impression cylinder has past the rollers 34, 35, and 36. Thereafter, the guiding device 11 again is moved in the opposite direction for guiding the next sheet. It will be understood that appropriate control and drive means may be provided for moving the guiding device 11 and swing gripper 10 in timed relation so that there is no interference in the movement of the parts.

During the period that the guiding device 11 is moving in unison with the sheet 16 being transferred, there will be little or no relative movement between the sheet and the rollers 34, 35, and 36. Even when the guiding device comes to rest near the blanket cylinder 15, since the rollers freely rotate as the sheet passes by them, the peripheral speed of the rotating roller will be equal to the speed of the passing sheet so that there still is no relative sliding movement. As a result, the risk of damaging or smearing of the sheets is substantially eliminated. Furthermore, since the rollers 34, 35, and 36 comprise a plurality of rolls in side-by-side relation, the force acting upon the sheet is distributed over a large enough area that pressure on the sheet will not damage the sheet or image.

In order to compensate for different thicknesses or stiffnesses of materials to be printed, the position of the guide rollers may be selectively varied. By pivoting the arm supporting rollers 35, 36 about the axis of the roller 34, the rollers 35, 36 may be moved relative to the impression cylinder, such as to the position 38 shown in FIG. 2. Further adjustments in the spacing of the guide rollers 34, 35, 36 relative to the impression cylinder may be obtained by adjusting the radial length of the yoke 40 through appropriate means. This would have the affect of altering the radial position of the first roller 34 as well as the other rollers 35, 36 which are mounted in cantilever fashion from the axis of that roller, such as shown by the line 37, in FIG. 1.

With the influence of the guiding device 11, as the leading edge of a sheet 16 is engaged by the impression cylinder grippers 30, the sheet will immediately be brought into close contact with the impression cylinder as it is carried about the cylinder. Nevertheless, as the sheet is being drawn about the impression cylinder, the trailing end of the sheet may still project a distance outside the effective range of the guide rollers 34, 35 and 36, especially in the case of relatively long sheets, and will occupy a position as shown in FIG. 1 so that interference with the swing gripper 10 returning to the feed table 12 is unavoidable.

In carrying out the invention, the swing gripper 10 is provided with at least two guide rolls 58, 59 which are mounted on axes parallel to the impression cylinder 14 such that they project beyond the contour of the swing gripper 10 and engage the trailing end of a sheet 16 carried by the impression cylinder as the swing gripper is returning to the feed table, thereby assisting in guiding the sheet into conformity with the impression cylinder while not marring the sheet. As best shown in FIGS. 4 and 5, the guide roll 58 is rotatably mounted on a stub shaft 60 in a recess 61 formed in the gripper 19. A releasable retainer spring 62 secures the stub shaft in mounted position in the gripper 19. By removing the retainer spring 62, the stub shaft 60 and roll 58 can be readily removed and replaced with one or more additional rolls in different positions. For example, FIGS. 6 and 7 show alternative arrangements by which rolls may be mounted on the gripper 19 of the swing gripper where particular graphic sectioning of the image requires positioning of guide rolls onto nonprinting areas. FIG. 7 shows additional guide rolls 64 mounted on the extension of a shaft 65 outside the center of the recess 61 of the gripper 19. The rolls 64 in this case are separated by a spacer 66 and held in position by a spring retainer 68. FIG. 6 discloses an arrangement whereby rollers 69 are mounted on a shaft 70 on either side of the gripper 19. For still other conditions, the roll 58 may be omitted from the recess 60. 7

The guide roll 59 is rotatably mounted in the gripper pad of the swing gripper 10 and also projects beyond the contour of the swing gripper. The gripper pad 20 in this case is bifurcated at its lower end and adapted to receive a journal 71 on which the roll 59 is rotatably mounted. A slotted portion 72 is provided for clamping the journal 71 of the roll 59 so that no further clamping elements projecting in a lateral direction is required. As in the case of the roller 58, additional rolls on one or either side of the gripper pad may be provided as specific printing conditions require.

The operation of the swing gripper on its return movement to the feed table is schematically shown in FIG. 3. Successive positions of the gripper are indicated by the letters A,.B, C, and D, and the parts of the swing gripper and the sheet at each position are given the same reference numeral described above with the distinguishing suffix a, b, c, or d, added respectively. Position A illustrates the returning swing gripper 10a as it begins to engage the sheet 16a being transferred by the impression cylinder 14. In this position only the rolls 59a of the gripper pad 20a contact the sheet surface, deflecting the sheet 16a as indicated at 80. As seen in position B the sheet represented by the line 16b is contacted at 81 and 82 by the rolls 58b of the gripper and the rolls 59b of the gripper pad 20b, respectively. The dash-dotted position C shows only the gripper roll 58c being in contact with the trailing edge of the sheet represented by the line 16c. The rolls 59c of the gripper pad 200 being in uplifted position have no further contact with the sheet. In position D the swing gripper has returned to the feed table to engage another sheet. It will be appreciated that since only the rotatably mounted rolls 58, 59 of the swing gripper engage the sheet, there is no sliding movement between parts of the swing gripper and the trailing edge of the sheet which might smear or damage the sheet. Moreover, the swing gripper serves to assist in guiding of the trailing end of the sheet into conformity with the impression cylinder. As the sheet continues around the impression cylinder, the trailing edge of the sheet eventually will be guided into close relation with the impression cylinder as it passes within the effective range of the rollers of the guiding device as explained previously. V

What is claimed is:

1. In a rotary printing machine for printing relatively heavy flexible sheets, said machine including a sheet feed table and a rotatable impression cylinder for successively receiving sheets and transferring them in a rotary direction for printing, a swing gripper having an arm with sheet engaging and releasing means at the lower end thereof, means for mounting said arm for reciprocating swinging movement so that said sheet engaging and releasing means moves between the table and said impression cylinder for successively transferring sheets therebetween, a guiding device for engaging successive sheets and gradually bending said sheets into close conformity with the outer periphery of said impression cylinder after each sheet is received and is being transferred by said impression cylinder, said guiding device including a plurality of rotatable guide rollers arranged on axes parallel to said impression cylinder along an envelope surface surrounding in spaced relation a sector of the outer periphery of said impression cylinder and said swing gripper having at least one roller rotatably mounted at the sheet engaging end thereof mounted on axes parallel to the axis of said impression cylinder for engaging the trailing end of a sheet being transferred by said impression cylinder to assist in guiding said sheet in the direction of said impression cylinder as said swing gripper returns to said feed table for the next sheet.

2. In the rotary printing machine of claim 1 in which said guiding device is mounted for reciprocating movement about the axis of said impression cylinder to permit movement of said guide rollers in a reciprocating manner about a portion of the outer periphery of said impression cylinder.

3. In the printing machine of claim 1 in which said sheet engaging and releasing means includes a gripping finger and a gripping pad, and at least one of said rollers is rotatably mounted on said gripper finger and another of said guide rollers is rotatably mounted on said gripper pad.

4. In the rotary printing machine of claim 1 in which said guiding device includes a yoke mounted for pivotable movement about the axes of said impression cylinder, and means pivotably mounted at the outer end of said yoke for supporting and selectively positioning a plurality of said guide rollers in predetermined spaced relation to said impression cylinder.

5. In the rotary printing machine of claim 4 in which a first one of said guide rollers is rotatably mounted at the outer end of said yoke, and said roller support means is mounted for pivotable movement about the axis of said first roller.

6. In the rotary printing machine of claim 4 in which said guide rollers each comprise a plurality of individual rotatable rolls, said rolls being removably mounted on said support means and selectively positioned in an axial direction.

7. The printing machine of claim 6 in which said guide rolls are made of synthetic material and have a metallic coating on their outer peripheral areas. 

1. In a rotary printing machine for printing relatively heavy flexible sheets, said machine including a sheet feed table and a rotatable impression cylinder for successively receiving sheets and transferring them in a rotary direction for printing, a swing gripper having an arm with sheet engaging and releasing means at the lower end thereof, means for mounting said arm for reciprocating swinging movement so that said sheet engaging and releasing means moves between the table and said impression cylinder for successively transferring sheets therebetween, a guiding device for engaging successive sheets and gradually bending said sheets into close conformity with the outer periphery of said impression cylinder after each sheet is received and is being transferred by said impression cylinder, said guiding device including a plurality of rotatable guide rollers arranged on axes parallel to said impression cylinder along an envelope surface surrounding in spaced relation a sector of the outer periphery of said impression cylinder and said swing gripper having at least one roller rotatably mounted at the sheet engaging end thereof mounted on axes parallel to the axis of said impression cylinder for engaging the Trailing end of a sheet being transferred by said impression cylinder to assist in guiding said sheet in the direction of said impression cylinder as said swing gripper returns to said feed table for the next sheet.
 2. In the rotary printing machine of claim 1 in which said guiding device is mounted for reciprocating movement about the axis of said impression cylinder to permit movement of said guide rollers in a reciprocating manner about a portion of the outer periphery of said impression cylinder.
 3. In the printing machine of claim 1 in which said sheet engaging and releasing means includes a gripping finger and a gripping pad, and at least one of said rollers is rotatably mounted on said gripper finger and another of said guide rollers is rotatably mounted on said gripper pad.
 4. In the rotary printing machine of claim 1 in which said guiding device includes a yoke mounted for pivotable movement about the axes of said impression cylinder, and means pivotably mounted at the outer end of said yoke for supporting and selectively positioning a plurality of said guide rollers in predetermined spaced relation to said impression cylinder.
 5. In the rotary printing machine of claim 4 in which a first one of said guide rollers is rotatably mounted at the outer end of said yoke, and said roller support means is mounted for pivotable movement about the axis of said first roller.
 6. In the rotary printing machine of claim 4 in which said guide rollers each comprise a plurality of individual rotatable rolls, said rolls being removably mounted on said support means and selectively positioned in an axial direction.
 7. The printing machine of claim 6 in which said guide rolls are made of synthetic material and have a metallic coating on their outer peripheral areas. 